


Koutarou and Keiji's Egg-cellent Adventure

by CharWright5



Category: Haikyuu!!
Genre: Aged-Up Character(s), Akaashi Keiji has Kinks, Alpha Bokuto Koutarou, Alpha/Beta/Omega Dynamics, Anal Fingering, Anal Sex, Bottom Bokuto Koutarou, Egg Laying, Eggs, M/M, Oh god how to tag this, Omega Akaashi Keiji, Oviposition, Sex Toys, Top Akaashi Keiji, not eggpreg though, ovipositor, the Splorch
Language: English
Status: Completed
Published: 2019-05-12
Updated: 2019-05-12
Packaged: 2020-03-01 15:42:12
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,693
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18803317
Author URL: https://archiveofourown.org/users/CharWright5/pseuds/CharWright5
Summary: Keiji has kinks and Koutarou has a lot of love for his Omega, even if it results in him getting gelatin eggs to his butt.





	Koutarou and Keiji's Egg-cellent Adventure

**Author's Note:**

  * For [ItsAiryBro](https://archiveofourown.org/users/ItsAiryBro/gifts), [x_Lazart_x](https://archiveofourown.org/users/x_Lazart_x/gifts).



> Oh man okay...
> 
> So the Please Bokuto-San zine discord is to blame for this one, specifically Airy and Steph (whom I am sure regret Nothing) so... This is partially mostly on them.

Koutarou wasn't like most Alphas.

Which, okay, putting it that way made him sound like one of those tumblr posts about how someone was "not like most girls" or Amy Poehler in _Mean Girls_ who was "not like most moms, I'm a cool mom".

But... it was kinda true.

Most Alphas got stuck on biology and anatomy and instinctual bullshit rigidity that told them they were the penetrator and penetrator only. But for Koutarou, that just sounded dumb as hell. Why would he give up the opportunity to have his own hole, his own prostate played with? Why wouldn't he take advantage of all the world had to offer in terms of lubricants and toys and the like? Why would he turn down whatever kink his Mate wanted to try out next?

Because Keiji had kinks.

_A lot_ of kinks.

And Koutarou was stupidly in love--and whipped, according to Kuroo, who had exactly zero room to talk--and would do anything to make Keiji happy.

Okay, maybe he was whipped.

Definitely whipped, judging by this new idea and the fact that, yeah, he had totally agreed to Keiji's new fantasy.

He blamed hentai, honestly. Keiji clearly watched too much of it and it gave him _ideas_. But since Keiji's ideas always turned out to be awesome and he couldn't say too much when his beautiful, selfless Omega also went along with his own crazy desires, he agreed to join in with his Mate's wild and crazy plans.

Even if it cost over sixteen-thousand yen--not including shipping and handling--and nearly two months of wait time for it to arrive.

_It_ , of course, being an ovipositor dildo, two sets of four egg molds, and an egg insertion tool. So Keiji could essentially stuff Koutarou full of gelatin eggs and watch him lay them.

Koutarou figured there were weirder things he could put in his butt and that at least it wasn't real eggs. And with Keiji having done tons of research beforehand--because studying and overanalyzing was his thing, always had been--Koutarou knew there was no real danger of anything, except for a big mess at the end. Which was kind of a kink of his own, so really, no harm no foul.

The toy arrived in a plain brown package with no hint to its contents whatsoever, something that was a great relief to Koutarou, who'd been plagued by nightmares of the nice old lady across the hall finding it and him having to explain what the hell an ovipositor was, why they bought it, what they were planning to use it for. It also saved him any weird looks from the mailman upon receiving it, although he had a feeling the guy probably had delivered countless sex toys over the years, some not as discreet as the one Koutarou had gotten.

Nevertheless it was there, Keiji was opening it on their kitchen counter, and...

And Koutarou was overcome with a giant giggle fit. Because for starters, the one they'd decided on was called "The Splorch", a name that had him snickering just by thinking about it. Secondly, the toy was teal with a black base--Keiji's choice, Koutarou pointing out that it didn't matter what colors went up his butt since he wouldn't be the one seeing it, although he was a little disappointed they'd decided against the glow in the dark option. Third, it...

Well, it was kinda weird looking.

Although maybe that was kinda the point? It was more of a sci-fi toy, more for alien fuckers and monster fuckers he figured. It wasn't supposed to resemble anything human. The black base kinda looked like a vagina though, or at least the lips of one, with a long phallic-like tube tentacle thing coming from the middle. It was surprisingly veiny, too, very detailed, rounding off at the end with a fairly decent sized split that was clearly where the eggs would come out. Koutarou couldn't help moving the two sides together like a mouth, making loud "mwamp!" noises as he did, stopping at the sight of the clearly disapproving deadpan look he got from his Mate.

"So this is an alien dick, huh?" Koutarou asked as he inspected the thing, Keiji more interested in the instructions for how to make the eggs in the molds.

"Ovipositor," the Omega corrected, eyes still on the half sheet of paper. "And it's what females have to lay eggs inside someone so it's not a dick."

Huh. Explained the base of it, Koutarou thought, turning it over to find the hole where the eggs would initially be inserted. Overall the whole thing was well made, flexible, pliable, soft to the touch so it could expand and push eggs through, yet firm enough to go into someone, rigid enough to not lose its shape. Koutarou couldn't help wrapping his hands around the shaft-tentacle-whatever and stroke it, squeezing it experimentally. It was nothing like the dildos Keiji had used on him before, nothing like Keiji's cock itself.

Really, that was kind of the point of "experimenting", doing something new and different and maybe even a little weird to find out what worked and what didn't. From the feel of it in his hand, Koutarou started thinking this thing would actually work for him, veins rubbing against his walls, eggs pressing against his prostate.

He shuddered just thinking about it, cock giving an interested twitch of its own. Yeah, he wasn't gonna have much of a problem letting Keiji fuck him with this, pretending Keiji was some sexy alien from planet Hot as Fuck impregnating him with his eggs or depositing his eggs or whatever.

Which...

Koutarou frowned, turning to find Keiji pulling out a measuring cup from its home cabinet. "Does that make you an alien chick then?"

Keiji glared ferociously and Koutarou got kicked out the kitchen.

~*~*~*~*~*~

They couldn't do it that night, since it was a Monday and they had work the next day and the mail had arrived in the late afternoon. But they had all day Saturday to play around and have fun and deal with what was rumored to be a hellacious clean-up, so they made plans to use their new toy then.

Which meant Koutarou spent the next four days thinking about it, taking the ovipositor out of their special drawer to check it out over and over again when Keiji wasn't around, enjoying the give of the silicone and the fantasy of how good it would feel inside. He also had a couple wet dreams involving Keiji as a sexy alien fucking him full that had him waking up before his alarm and greeting his Mate by eating him out.

Then there were the gelatin eggs, still in their plastic molds, sitting in the fridge right next to the milk and the orange juice. Koutarou spotted them every time he opened the door to get something, narrowing his eyes as they taunted him with the promise of _soon_ but _not soon enough_.

By the time Saturday arrived, Koutarou felt like he'd suffered through four days of foreplay. The teasing looks Keiji had given him over that time didn't help, dirty talk over how he could wait to stuff the Alpha full with his eggs, watch him lay them just for his Omega like the good boy he was... Yeah, torturous.

Despite the waiting and fantasizing, despite the teasing words and extensive planning, despite the cleaning and prepping, when the time finally came to do it... well, Koutarou had a hard time believing it was actually happening. Sure, being facedown on the bed, ass raised in the air, three of Keiji's slender and talented fingers stretching and rubbing and teasing all the right places inside him. But usually the prep work wasn't for something like _this_. And generally they didn't have a literal stack of towels off to the side, with three or four layered underneath him.

Except for that one time Keiji let Koutarou fist him, but considering the amount of lube they'd used in addition to the Omega's natural slick... 

They were probably gonna need a lotta lube this time, too. Koutarou had already fiddled around with one of the gelatin eggs--and warned not to eat it, which he wasn't going to because it didn't smell as good as the actual dessert type--and he got the feeling they weren't going anywhere without a little help.

Previously described talented fingers pressed at his prostate, making Koutarou jolt and cry out as all thoughts flew out his head. A tender kiss was placed at his tailbone, Keiji's free hand stroking his thigh as he let out a purr that had Koutarou answering with a rumble of his own. The air was thick with the scent of synthetic lubricant, gelatin, and silicone, as well as arousal, anticipation, and nerves. Although Koutarou honestly wasn't sure if that last one was coming from him or Keiji or both of them.

He liked to think both, that he wasn't alone in this, but he also hated the thought of his Mate being anxious over anything.

Propped up on a forearm, he reached back and took hold of the hand currently petting his thigh, squeezing it in assurance. "Ready when you are," he stated, shooting a lopsided grin over his shoulder and getting a soft smile in return.

Keiji moved up to give him a quick yet passionate kiss, a hard press of their lips. Then with one last run against his prostate, those fingers--sadly--slipped out of him.

The snap of the lube bottle cap sounded loud in the otherwise silent room and Koutarou took a deep breath, slowly letting it out in a shuddery exhale. He let his mind drift, reminding himself that it was gonna be that big a deal. Okay, so it was longer than anything he'd had in him before but that didn't mean he had to take it all. And it wasn't all that round girth-wise--without the eggs anyway--and it was flexible. No biggie.

Fingertips rubbed at his entrance, extra lube added, and Koutarou bore down to open himself up more. The sweet scent of pleased, aroused Omega hit his nose and he let out a rumble at it, at the feel of silicon veins rubbing against him as Keiji teased the toy along the cleft of his ass.

"Hold yourself open for me."

It was a request he made towards the Omega often, only not quite with the same teasing lilt that Keiji managed. It definitely had the right effect though, Koutarou shifting so he was leaning on his shoulders, hands reaching back to grip his cheeks and spread them. He felt exposed, the Alpha in him railing against it, the main part of him saying to shut the hell up. He trusted his Mate.

"Good boy," Keiji purred and Koutarou felt his chest get warm, felt it puff up in pride, felt... felt Keiji's thighs hit against his as he continued to rub the toy, the ovipositor along his cleft.

"Tease," he pouted.

Keiji laughed. "Vengeful."

Okay, yeah, Koutarou probably had it coming, considering the number of times he pulled this same crap.

He heard the lube cap pop open, more of it squelching out in a way that made a giggle fight up from his chest, amused in a childlike way and also a little nervous. A tap to the side of his thigh was the only reprimand and he pressed his lips into a hard line and forced himself to sober up.

As soon as he did, he felt the silicon tip slide inside him.

A whimper escaped him and he had to battle against the way his body wanted to close up, tighten up, keep the invader out. Keiji paused briefly, only moving when Koutarou nodded, loose hair ruffled against the sheet below him. It felt strange, so different from what he'd had inside him before. There was no glans, no mushroom head popping in. It felt softer than anything he'd ever taken in, too, able to be squished by his inner-walls. 

Which he did.

Because it felt pretty damn good to have those veins rub against him, against his rim, the shaft of it widening slightly as he got closer to the bottom.

Keiji paused to let him breathe when he had half inside, asking if he wanted more, and at that point, Koutarou was determined to take the whole thing. It was a matter of pride, a refusal to not disappoint his Mate, a need to show off and prove Alphas could fit something that long inside.

Not that it was easy, fuck no. It felt like it went beyond the capacity of his passage and he had to relax further, had to arch his back more to get the right angle. But eventually, he felt the base against his ass and Keiji's thighs against his own, the Omega more than likely holding the toy to his own pelvis.

"How's it feel?"

Koutarou snorted, wiggled his hips back and forth, felt a lopsided grin form on his face. "Like I have a silicone tentacle in my ass."

Hips slammed against his in warning and Koutarou could practically feel the eye roll. "Ovipositor."

"Po-tay-to, po-tah-to."

Another hip slam and he didn't bother holding back the laugh. "Behave," Keiji warned, smacking his thigh again.

"Sorry." Koutarou cleared his throat, sobered up again, peered over his shoulder with his best apologetic and pleading face. "Please fuck me with your big ovipositor and fill me with your eggs." He felt utterly ridiculous saying it and it was a struggle to keep his face straight and in the back of his mind he registered that Kuroo could never find out about this or else Koutarou would never live it down.

But the words had their intended affect on Keiji, his eyes flashing Omega gold and going heavy lidded, his teeth sinking into his bottom lip, the flush on his face deepening, and the scent of his arousal growing stronger. Fuck, he was beautiful like this, kneeling behind Koutarou's prone form, hips pressed to his ass, horny as hell. It was why Koutarou went along with shit he thought was ridiculous and too out there for him, because Keiji wanted it, and wanted it with him, and looked so goddamn good doing it.

Moving his hips back, Keiji slid the ovipositor/ tentacle/ dildo back, the veins dragging against Koutarou. Pushing it back in was a bit of work given the flexibility of it, but the Omega made it happen, slowly fucking his Mate with the toy.

"Next time, we should use the harness with this thing," Keiji grunted from exertion.

"Next time," Koutarou began, pausing to huff out a deep breath. "I get to fuck the eggs into you."

A shiver, a breathy laugh, and an erratic thrust. "Okay," Keiji practically squeaked and Koutarou grinned, glad he'd gotten to his Mate again.

Victory was always pretty damn sweet. Especially when it smelled like an aroused Bokuto Keiji.

Pushing the toy all the way inside, Keiji paused and leaned over Koutarou's back. The Alpha rumbled happily at the skin on skin contact, at the feel of his Mate's pounding heart against his back.

"You ready to take my eggs?" he purred right in Koutarou's ear before nuzzling against his neck. Totally unfair.

Especially when those words hit some strange primal nerve deep inside, that breeding instinct that still resided despite centuries of evolution. Alphas were made to breed, to create the next generation, and to protect and provide for them. It didn't matter to the basic part of him that it wasn't done by egg laying or by having something implanted inside him or that this entire thing was role playing. No, the words still had him groaning, still had him arching his back to present as much as he could, still had his cock spurting out precome onto--hopefully--the towel below and his knot throbbing like it was getting still to expand.

Oh fuck. As much as he was dying to let Keiji do his thing, he was just as desperate to bury his cock in his Mate and fill him up, too.

"Koutarou?"

Right. He was supposed to answer. Verbal consent in all they did at all times, making sure the other person was still okay with everything.

Swallowing the lump in his throat, Koutarou nodded, sweaty forehead rubbing against the sheet. "Yeah," he answered, voice shaking so slightly that only Keiji would be the one to pick up on it. "Yeah, I'm ready."

A smile was pressed to the side of his neck, then a kiss right over his swollen scent gland, a bite to the scar around it signifying their Mating. Keiji raised his body back up, his thighs moving away from Koutarou's, shuffling around as he got comfortable. The lube cap snapped open again, more squelching, a slick sound Koutarou assumed was an egg--or more--being coated.

Then a snicker that had him peering over his shoulder to find Keiji grinning as he picked something up off the towel on the bed. "They're really slippery," he explains with a grin when he realized he was being watched.

Koutarou snorted. "Good thing these won't crack then."

"Nope. Just melt inside you."

Man, he was glad he knew it would be safe if that happened, otherwise he'd be freaking out over getting sick.

"Ready?" Keiji asked again and Koutarou nodded, taking a deep breath then letting it out, relaxing his body all over.

He heard the squelching sound of a lube-coated egg being handled, the frustrated groan of Keiji having trouble pushing it into the hole at the base of the ovipositor, then...

Then he felt pressure on his rim and once again, he bore down to accept what was trying to come through. The stretch wasn't anything major, a few centimeters around at most, just enough to be felt, just enough for him to groan at the stretch. Something pushed it further along, Keiji's fingers he assumed, and his entire body jerked when the girth of the egg caused the veiny shaft of the toy to rub against his prostate.

"You okay?" Keiji checked in.

Koutarou let out a "yeah" then wiggled his hips. "Gimme another."

More squelching, the next egg popping inside easier, pushing the first down further. A brief pause before the third joined, the ovipositor full, Koutarou in a similar state and moaning.

"How's it feel?" Keiji checked in, rubbing Koutarou's flank with a lube sticky hand.

The Alpha grunted in pleasure, arching and straightening his back repeatedly, hips moving as though he were fucking into something. "Different," he exhaled, breathing more shallow and erratic now. "Not bad. Not _full_ full but maybe getting there. It's weirdly good."

Keiji let out a thoughtful hum. "Think you can take another?"

Koutarou squeezed his inner walls, felt the eggs shift, the toy squish. He remembered Keiji had made both four-egg trays as a precaution, in case some didn't come out right, but the gleam in his eye told Koutarou his Mate had been hoping to fit them all.

And considering he felt like he still had room inside--and that whole pride thing--he felt up to the challenge.

"Yeah. Gimme all your eggs, baby."

Once again, the words felt slightly ridiculous but they struck the right note with Keiji, his scent bursting like before. More lube being poured out, another grunt of frustrated exertion, before Koutarou felt an egg pop out of the ovipositor itself and into his actual body. He gasped at the sensation, as it hit against something inside, and his fingers clutched at the sheet as a low groan made its way out.

"Okay?"

A nod, a breathy "keep going", another egg forcing the next in line to push out and into him. It was weird, slimy, made his insides feel... _gooey_ for lack of better terms. Not super gooey though, not gross or anything. Just... aware that they weren't real eggs.

No wonder all the warnings said it would be messy.

With a nod from Koutarou, the next was added, three eggs inside him, three more in the ovipositor, the final two still in the bowl. He was starting to feel stuffed, full, and his hand dropped to his lower abdomen, feeling a slight bulge there that he wasn't entirely sure he was imagining. His body was shaking from holding himself in that position, breathing still heavy, Keiji's aroused scent thick in his nose.

"Go 'head," he slurred. "Gimme las' two."

He could hear Keiji swallow, felt his hip being squeezed reassuringly. Without pause, the final two eggs pushed in, then Keiji manually pushed the next in with his fingers inside the ovipositor. Koutarou groaned with each egg that popped inside of him, whined as he felt the toy draw back until the two eggs inside caught on his rim. He wasn't sure what was going on behind him, something being grabbed--probably the hard plastic took that came with to push the eggs through--before finally, _finally_ the final two pushed out of the ovipositor.

Oh shit. Now he really _was_ full, but also weirdly not. The eggs easily squished when he flexed his passage, making him all too aware of what they were made of and how they could simply melt in there.

Nope. No thanks.

Not to mention it wasn't what Keiji wanted to see.

He moaned as the ovipositor slowly slid out of him, his hole gaping around nothing and he clenched tight automatically to prevent anything from escaping. Lubed hands slid up his sweat slick spine, soothing, gentle, and he arched into the touch with a rumble. A trail of kisses followed, Keiji pressed himself against his back again, hands drifting around and down to his lower abdomen. Koutarou felt as much as heard the purr his Omega let out as he nuzzled against his damp hairline, hips rocking, hard cock sliding between his cheeks, making Koutarou wish there was room inside for Keiji to fuck him with that, too.

"How's it feel?" Keiji asked, sounding breathless as his fingers prodded at Koutarou's stomach, feeling the eggs he'd implanted his Mate with.

"Kinda full. Lil slimy. Dying for you to fuck me right now."

A pleased hum then the tips of three fingers breached his hole, reaching in to touch what he'd slipped inside. "I can feel one. Can't believe you let me fill you like this. And you took all eight." He groaned, scent sparking, and Koutarou grinned in pride, thrusting back against the long digits invading him.

"I'll take anything you give me," he answered, fingers slipping out to rub at his entrance. "Ready for me to lay them for ya?"

A swear ghosted over his spine, making him shiver. Those talented fingers he loved so much slipped away and he mourned their loss with a whine, even as he felt Keiji's hands slide up his sides, under his pits, over to splay across his pectorals. "Up on your knees. Might be easier."

It took a bit of shuffling, but soon Koutarou was kneeling on the bed, towels spread out under and around him. He moved up enough so that he could grab hold of the headboard for leverage, for something to grip, pillows all tossed onto the floor for safety. Keiji was sitting on his heels somewhere behind him, close enough to rub at his thighs and the side of his ass, close enough for Koutarou to pick up on the notes of excitement and anticipation in his scent.

"Ready when you are," the Omega announced and Koutarou took a deep breath.

And felt kinda ridiculous.

God, was he seriously about to...

Yeah, yeah he was. Because it was what his Mate wanted and Keiji was amazing enough to along with his weird kinks and fantasies and he himself was whipped enough to do whatever Keiji wanted him to.

Reaching back with one hand spreading himself open, the other gripping the headboard, Koutarou bore down once more. He felt a shifting inside, felt the gooey eggs squish but move down his passage. Another deep breath, another push, and he fought away the urge to engage in any weird labor breathing pattern.

He was kinda giving birth though. Kinda, if ever any of them--

He felt a pressure at his rim and he adjusted the hold on his glute, tried to spread himself more, grunting as he pushed and pushed and--

The first egg came out with a squelching plop and a soft swear from behind, Koutarou's own breath shuddering. Again Keiji's arousal kicked up a notch and Koutarou used it as motivation to push the next one out, then the next, then two right after each other. Then...

Then...fuck.

Keiji pressed up against his back, trailing wet kisses and light nips over his trapezius, the side of his neck, his Mating bite. One hand began playing with his hole, fingering him, scissoring to stretch him. The other hand wrapped around his cock and began slowly stroking and Koutarou practically melted against his Mate, against his strong, beautiful, kinky Omega who was currently working him up even more than ever.

"Oh fuck, Kei," he groaned, head falling back, eyes shuttering closed.

"Such a good Alpha for me," Keiji purred in his ear. "I can feel the next one inside you, it's so close. Bear down for me, baby. Lemme have it."

Shit, his voice was pornographic velvet, gliding over Koutarou, teasing all the right places. Tired inner muscles and burning lungs were hit with new life and he did as he was told, pushing down. Keiji kept his rim stretched open with skinny fingers and allowed the next egg to fall out. A quick pause to catch his breath then he was able to get the penultimate one out. The final one gave him issues once more and Keiji had to slip his fingers inside to help guide it down, knuckles inadvertently rubbing against Koutarou's prostate and making him shudder, shake, groan...

The final egg was expelled from his body without much ceremony, Koutarou groaning in relief, Keiji groaning in arousal. Releasing the grip on his ass, Koutarou reached back to cup the back of his Mate's head, turning to kiss him hard.

"Fuck me, Keiji," he panted out, watching slate eyes flash gold.

"Won't last."

"Shit, me neither."

Apparently satisfied with that response, Keiji thrust his hard cock inside, only pausing long enough to adjust his stance. The thrusts were sloppy, erratic, stirring up the mess Koutarou could feel inside but no less pleasant for any of it. He let himself get lost in the sensations, of being filled by the man he loved and his walls being rubbed pleasantly and his cock being stroked just right. Keiji was shaking, panting hard against his neck, whining in desperation the way Koutarou always loved.

It didn't take long for Koutarou to come, shooting out freely. He worked his inner walls, squeezing and massaging, helping his Mate reach his own end and soon feeling the mess inside him get messier, hotter, hot streams filling him up. Fuck, feeling Keiji come was almost as good as actually coming himself, and he shuddered all over at the sensation.

"You feel so good," Koutarou groaned, squeezing the arm that had snaked around his waist at some point. A moan was the only response he got, Keiji still moving his hips, stirring up his insides even more.

When he was satisfied, the movements stopped and Keiji pulled out, leaning over Koutarou's shoulder to kiss him deeply. It was a "thank you" and a "love you" wrapped into one and Koutarou let himself get carried away in the feeling of his Mate's lips against his own. Soon they were gonna have to clean the mess, toss the eggs in the sink to melt, towels in the washer to get rid of various stains, themselves in the shower to clean inside and out. For now though... for now, this. Just two men sharing their love for one another.


End file.
